The cause of bulimia nervosa is incompletely understood however animal and human studies have implicated the endogenous opioid system in feeding behavior. We hypothesize that there are both trait and state-related differences in the distribution and modulation of the opioidergic system that underlie the reinforcing quality inherent in this behavioral disorder. We propose to use positron emission tomography (PET)-scanning to measure mu-opiate receptors in patients with bulimia nervosa before and after treatment and in control women. Pilot data suggest a relationship between opioid receptors and the etiology or symptoms of bulimia. We propose to elucidate this relationship and to examine its change with treatment, specifically with normalization of eating behavior. The specific aims of this study are to: 1) Measure regional brain mu opioid receptors by PET in female patients with bulimia nervosa and matched normal controls. 2) Measure the change in regional mu opioid receptors by PET before and after cognitive behavioral therapy (CBT) of patients with bulimia nervosa It is anticipated that elucidation of the role of the endogenous opioid system in bulimia nervosa will not only help elucidate the etiology of this disorder, but also bring about new approaches to diagnosis, long-term risk assessment, and monitoring of treatment.